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Fall 2004 Issue |
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The Cushcraft ASL670 |
All of the Cushcraft ASL670 parts prior to assembly. |
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Recently, my interest in the VHF/ UHF bands returned after an absence of many years. My first introduction to the VHF bands was when I operated 6 meters back in my high school days (1965) during Field Day with a club in Maryland. I was WA3BCQ back then. Shortly after Field Day, I purchased a Lafayette HA-650 1-watt AM 6-meter rig and a Cushcraft 6-meter Squalo antenna. I mounted the antenna on my dad’s chimney, and for the next several years I had a ball on that band. When conditions were right, the possibilities with my modest low-power setup on that “magic” band absolutely amazed me. I worked into Cuba and Mexico. Quite frequently, I worked halfway across the country.
Fast forward to 2004. Now I am an HF CW
operator. Lately I’ve been exploring possibilities with my ICOM
IC-706MKIIG (used strictly for portable operation until now), and I have
been wondering about those higher frequency bands that I haven’t operated
in years. With a little pressure from Bill Conner, K5GMX, and Paul St.
John, N6DN, I decided to get back on 6 meters. I was also curious about
the activity on 2 meters and 70 cm, so I decided to work those bands as
well. In considering these three bands and my environment, my dilemma
became which antenna would best be suited for my situation. I live on a relatively small lot, with no real room for a tower. Consequently, my HF operation is accomplished with a ground-mounted Butternut HF-9V, which is located in a corner of my yard. The advantage of VHF/UHF antennas is that they are relatively small and therefore can be roof-mounted. Even so, multi-band coverage can make for an “ugly installation” (non-ham term for antennas) if multiple antennas are required, even if the antennas are small in size. There is a solution, however, if one considers using a log-periodic antenna. The log-periodic is a broadband antenna that can cover multiple ham bands. A great deal of information on these antennas can be found in the ARRL Antenna Handbook, and I won’t rehash it here. With the log-periodic, some gain over separate antennas is lost, although the trade-off is not that bad. As an example, a 3-element, 6-meter beam has a forward gain of 8 dBi, whereas a same-length (6-foot) log periodic has a forward gain of 6.5 dBi. I’m willing to trade 1.5 dB for a single multi-band antenna. The antenna I chose is the Cushcraft ASL670 log-periodic, which offers continuous coverage from 50 MHz through 450 MHz. The antenna is no larger than a TV antenna. It even resembles a TV antenna, and it can easily be rotated with an inexpensive TV rotator. The ASL670 specs are listed in Table 1. |
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